The present invention relates in general to automated systems for positioning a sample, or cargo. More particularly, the present invention relates to a robotic positioning system and method that include a gross positioning system for movement of the sample between workstations and a precision positioning system for precisely locating the sample at the workstation with respect to a device that will interact with the sample.
Various industries require automated systems for the general movement of goods between workstations and a more precise positioning system for precisely locating the goods at each workstation for manipulation of the goods by a device at the workstation. For example, for pharmaceutical research and clinical diagnostics, there are several basic types of automation systems used. Each of these conventional approaches is essentially a variant on a method to move liquid or dry samples from one container to another, and to perform other operations on theses samples, such as optical measurements, washing, incubation, and filtration. Some of the most common automated liquid handling systems include systems such as those manufactured by Beckman, Tecan, and Hamilton.
These conventional automation systems share the characteristic that sample transfer and manipulation operations are carried out by workstations, or devices, of some kind. These workstations can be used separately for manual use, or alternatively, can be joined together in automated systems so the automation provider can avoid having to implement all possible workstation functions. Another shared characteristic is that samples are often manipulated on standardized xe2x80x9cmicrotiter plates.xe2x80x9d These plates come in a variety of formats, but typically contain 96 xe2x80x9cwellsxe2x80x9d in an 8 by 12 grid on 9 mm centers. Plates at even multiples or fractions of densities are also used.
In a first automation system, various workstations are linked together with one or more plate carrying robots. These robots can be a cylindrical or articulated arm robots, and can be located on a track to extend their range. A variant on this design is a system with one or more Cartesian robots operating over a work surface. In the Cartesian case, the robots can carry plates and also perform liquid transfer operations. These systems are controlled by a central control system with a scheduler. Most schedulers schedule the operations of one protocol performed many times, making sure that all time constraints are met, including, for example, incubation periods. The primary advantage of such a system is complete hands free operation. Accordingly, these systems can run for hours or days at a time with no human intervention. However, these types of systems have several disadvantages.
For example, individual devices can only be kept busy 30-70% of the time due to scheduling and collision avoidance constraints. In addition, the system has an upper limit on scalability. This second disadvantage comes about due to upper limits in achievable servo system dynamic range. All plate and liquid transfer operation require precision of about 0.1-0.5 mm. To do meaningful work, a work area of at least one square meter is typically needed. Servo systems that can achieve this dynamic range are expensive and relatively large. To increase the useable work area, dynamic range must be increased, without compromising the accuracy of the system. For these reasons, the largest linear dimension typically used is three meters. Smaller plates can increase the amount of work that can be accomplished in a given area, however, the necessary size of the high dynamic range servos prevents plates being used that are much smaller than the current standard.
A second basic type of automation can be created by using plate stackers. For example, an input stacker is placed on one side of a device such as a liquid transfer system or optical plate reader, and an output stacker is placed on the other. Plates are fed from the bottom of the input stacker to the device by conveyer belt or pick-and-place arm. When the device finishes an operation, the plate is similarly placed on the bottom of the output stacker. Stackers often use removable cartridges so that approximately 20 plates at a time can be carried from device to device. The cartridges are usually carried manually, however at least one system exists that uses an articulated arm robot to move the stackers between devices. Plate incubation is achieved by simply setting the stack in an incubator. The primary advantages of this automation approach are that the devices can be utilized nearly 100% of the time, and that it is relatively inexpensive to implement. However, this type of system has several disadvantages, including that the system is usually not fully automatic, that the plates cannot be processed with identical timing because the stacks are first in, last out, and that system flexibility is severely limited because stacks of plates must all be run through the same processing steps.
Another basic type of automation system is an extension of the above stacker type system wherein multiple devices are placed in a row on a lengthened conveyer. Although this system offers even more potential throughput, this type of system results in even less system flexibility. A further difficulty is that this type of system cannot accommodate incubation periods as there are no first in, first out stackers.
What is needed by various automation industries, such as the pharmaceutical discovery, clinical diagnostics, and manufacturing industries, is a sample positioning system and method that overcome the drawbacks in the prior art. Specifically, a system and method for providing a gross positioning system for moving samples between various stations coupled with a precision positioning system at each station for precisely locating the samples with respect to a device that will interact with the samples. Therefore, a need exists for an accurate sample positioning system and method that overcome the drawbacks of the prior art.
The present invention is directed to a system and method for positioning a sample, or cargo, with respect to a device in a robotic system. The system and method of the present invention provide both flexibility and scalability due to the benefit of queuing and the reduction in required dynamic range of the servos (e.g., actuators). The system and method of the present invention provide the flexibility of robots having autonomous navigation and stacker-like queuing for near 100% device utilization.
The system of the present invention includes a macro positioning system for xe2x80x9cgrossxe2x80x9d movement of the sample between stations and a micro positioning system for precisely locating the sample at a station with respect to a device that will interact with the sample. The macro positioning system provides a positioning mechanism for the general movement of a sample along pathways formed between various destinations, or stations, wherein the sample is xe2x80x9cgrosslyxe2x80x9d positioned with respect to the station. Once at the station, the micro positioning subsystem disposed between a sample carrier, or robot, and the station provides a positioning mechanism for xe2x80x9cpreciselyxe2x80x9d positioning the sample in a predetermined location at the station with respect to a device that will interact with, or perform some function on, the sample. The system and method combine technologies for macro positioning between stations, micro positioning at each station, and device interaction with the sample at each station in a robotics system for accurately positioning a sample with respect to a device that will interact with the sample.
The macro position system preferably includes some type of track system disposed between and connecting the various stations, and thus defining the pathways. The track system of the present invention can comprise any standard track system, including for example, a grid-type, miniature railroad type, line follower-type, slot-follower, light or laser-follower, magnetic-follower. The track system defines one or more pathways and intersections connecting the various pathways which allow the robots to travel between the various stations.
The system includes one or more carriers, transporters, or robots that carry a sample, or cargo, around the pathways. Each robot includes a body, a track engagement mechanism, a sample holding device, a power supply, and a propulsion mechanism for propelling the robot along the pathways. Preferably, the robots of the present invention have an on-board controller which provides for autonomous navigation of the individual robots between the various stations in the system. Multiple robots running on a track system provides system flexibility and stacker-like queuing for near 100% device utilization. Autonomous navigation of the robots allows greater system flexibility because each robot individually controls its own navigation thereby reducing required dynamic range of the servos. The robots are programmed to negotiate the track system and travel to predetermined destinations within the robotic system, where they interact with a device. In addition, the system and robots provide for collision avoidance, error recovery, robot to station communications/identification, and provide more flexibility and stacker-like queuing for near full device utilization.
The micro positioning system of the present invention is preferably disposed between the robot and the stations and is used to precisely locate the robot, and thus the sample, in a predetermined location in space. The micro positioning system includes a locating fixture on one of the robot and the station and a cooperating location fixture on the other of the robot and the station. Preferably, the location fixture includes one or more projection extending from the robot and the cooperating location fixture includes one or more depressions formed at the station. The projections fit within the depression to form a self-centering and precision fit.
A further embodiment within the scope of the present invention is directed to a method of positioning a sample, or cargo, in a robotic system with respect to a device located at a station in the system. The method includes providing for the gross positioning or movement of a sample along pathways formed between various stations and also for the precision positioning of the sample in a predetermined location in space relative to a device at the station in order for the device to be able to interact with the sample. The method comprises providing a plurality of predetermined pathways connecting one or more stations, disposing one or more robots along the pathways, activating a macro position system, which is preferably located on-board the robot, to move the robots around the pathways, xe2x80x9cgrosslyxe2x80x9d positioning the robots with respect to a station, activating a micro positioning system, which is preferably disposed between the robot and the station, micro positioning the robot, and thus a sample on the robot, in a predetermined location in space with respect to a device at the station, and interacting with, or performing some function on, the sample with the device based on the identification.
Preferably, the method of the present invention also comprises using some type of track system between the stations thus defining the pathways and providing a mechanism for the robots to travel along. In addition, the method preferably further comprises establishing a communications link and identifying the robot to determine whether the robot is at a correct location. Furthermore, the method can further comprise recovering lost robots using an error recovery system and avoiding collisions between robots using a collision avoidance system.
The system and method of the present invention provide for improved scalability both toward large and small systems, unlimited flexibility, allowing any sample to be processed following any protocol, stacker-like queuing for near 100% device utilization, and completely hands free operation.